Heat Curable Epoxy Compositions and Transparent Heat-Cured Coatings with Durable Adhesion Prepared Therefrom

ABSTRACT

The present disclosure provides heat-curable coating compositions for optical articles. The coating compositions include a multifunctional epoxy monomer in combination with a UV absorber. The inclusion of at least one multifunctional epoxy monomer and at least one UV absorber provide epoxy coatings that exhibit excellent adhesion on a variety of lens substrates.

FIELD OF THE INVENTION

The present disclosure relates to heat-curable epoxy coatingcompositions with UV filtering and durable adhesion, to methods forpreparing heat-cured epoxy coatings obtained therefrom, and to theoptical articles having such a coating.

BACKGROUND

In the optics field, optical articles may be coated with one or morecoatings such as impact-resistant, anti-abrasion/scratch-resistant,and/or antireflection coatings in order to impart various mechanicaland/or optical properties onto the articles.

In addition to the functional coatings identified above, opticalarticles may be given light-filtering functionality to prevent or limittransmission of specific wavelengths of light. The addition of afiltering function should be done without significantly modifying otherproperties such as abrasion resistance, transparency, or adhesion of thecoatings.

Blue light, sometimes referred to as high-energy visible (HEV) light,encompasses wavelenghts from about 400 nm to about 500 nm. Numerousstudies have demonstrated that cumulative lifetime exposure toblue-violet light near 430 nm causes photo-oxidation of retinal cellsthat leads to age-related macular degeneration (AMD). AMD is a leadingcause of blindness for people older than age 55. As the proportion ofsenior citizens in world-wide populations increases, AMD will reachepidemic proportions. To help control the harmful effects of blue light,ophthalmic lens manufacturers have implemented blue cut technology (BCT)to filter and reduce retinal exposure to harmful blue-violet and UVlight.

Generally, a coating composition is specifically adapted to one type ofsubstrate and does not provide sufficient adhesive properties on othersubstrates. The inclusion of blue cut dyes typically requiresmodifications to coating compositions in order to maintain a usefulbalance of adhesion, abrasion resistance, and low haze.

EP 3327091 discloses ophthalmic lenses coated with an epoxy-basedcoating obtained from a curable epoxy functional composition containingan absorbing dye blocking wavelengths which may present an impact on thehealth.

US 2018/113239 provides abrasion resistant UV-curable coatingcompositions for ophthalmic lenses comprising at least one epoxyalkoxysilane, at least one polyfunctional acrylate monomer and/orpolyfunctional epoxy compound, and at least one UV absorber.

While traditional epoxy coating compositions provide good initialadhesion on high-index optical substrates, these coatings show aremarkable adhesion decrease after prolonged exposure to full-spectrumsunlight. High-index optical substrates are known to degrade underprolonged exposure to the UV light, and a common solution is to add UVabsorbers into the substrates or coatings to prevent photo-degradation.Some UV absorbers may adversely interact with coating compositionchemicals during the curing process, leading to increased haze andreductions in dye absorption wavelength ranges. Therefore, there is aneed in the industry for curable coating compositions suitable for bluecut technology that exhibit good adhesion to a broad range of opticalsubstrates over prolonged exposure to sunlight.

SUMMARY

The inventors have found that the addition of a multifunctionalhydroxylated epoxy monomer to a heat-curable epoxy coating compositionresults in a moderate improvement in the adhesion of the resultingcoating to several optical substrates, including high-index lenses.Similarly, the inventors have also found that the addition of a UVabsorber comprising a hydroxyphenyl benzotriazole or hydroxyphenyltriazine can slightly improve adhesion. Neither addition, on its own,resulted in good adhesion after prolonged exposure to full spectrumsunlight. The combination of a hydroxylated epoxy monomer with a UVabsorber has been demonstrated to provide significant improvements inthe adhesion and durability of the resulting coating on a variety ofoptical substrates. Even after 80 hours of exposure to full-spectrumsunlight, the coatings do not lose adhesion. Moreover, the coatingsretain the low haze and high abrasion resistance necessary for desirableoptical articles.

The present disclosure is drawn to a heat-curable coating compositioncomprising at least one epoxy monomer comprising two or three epoxygroups, at least one hydroxylated epoxy monomer comprising at leastthree epoxy groups and one to three hydroxyl groups, at least one UVabsorber comprising a hydroxyphenyl benzotriazole or hydroxyphenyltriazine, and at least one epoxy ring-opening catalyst. The compositionmay further comprise at least one epoxy group and at least oneepoxysilane or hydrolysate thereof comprising at least one hydrolyzablegroup directly linked to the silicon atom. In some aspects, theepoxysilane is (3-glycidyloxypropyl)trimethoxysilane or hydrolyzed(3-glycidyloxypropyl)trimethoxysilane. In some aspects, the epoxymonomer does not include any hydrolyzable groups directly linked to asilicon atom. In some embodiments, the epoxy monomer does not includeany hydrolyzable groups directly linked to a silicon atom.

The epoxy monomers and hydroxylated epoxy monomers may comprise at least50% by weight of all epoxy-containing compounds present in thecomposition. In some embodiments, the epoxy monomer is a diglycidylether, a triglycidyl ether, or a cycloaliphatic epoxy. In some aspects,the hydroxylated epoxy monomer is sorbitol polyglycidyl ether. In someembodiments, the heat curable composition comprises two epoxy monomers,wherein one epoxy monomer is a glycidyl ether and the second epoxymonomer is a cycloaliphatic epoxy. In further embodiments, thecomposition comprises two epoxy monomers in which a first epoxy monomeris trimethylol ethane triglycidyl ether, a second epoxy monomer is3′,4′-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, and thehydroxylated epoxy monomer is sorbitol polyglycidyl ether. The epoxyring-opening catalyst may be an aluminum chelate, aluminum acrylate,aluminum alcoholate, triflic acid, or metal salt of triflic acid. Thecomposition may further comprise at least one absorbing dye. In someembodiments, the absorbing dye at least partially inhibits thetransmission of light in at least one selected wavelength range between380 and 1400 nm.

Some aspects of the disclosure are directed to a method for preparing anoptical article comprising coating an optical substrate with aheat-curable coating composition comprising at least one epoxy monomercomprising two or three epoxy groups, at least one hydroxylated epoxymonomer comprising at least three epoxy groups and one to three hydroxylgroups, at least one UV absorber comprising a hydroxyphenylbenzotriazole or hydroxyphenyl triazine, and at least one epoxyring-opening catalyst, and curing the resulting coating with heat. Thecomposition may further comprise at least one of an absorbing dye and atleast one epoxysilane or hydrolysate thereof comprising at least oneepoxy group and at least one hydrolyzable group directly linked to thesilicon atom. In some aspects, the method comprises coating the opticalsubstrate by spin-coating, spray-coating, 3D printing, roll-to-rollcoating, or inkjet printing. The coating may be heated to a temperaturebetween 60 and 140° C. to form a tack-free or completely cured coating.

Some embodiments of the disclosure are directed to an optical articlehaving at least one main surface comprising a coating obtained bydepositing on an optical substrate a heat-curable coating compositioncomprising at least one epoxy monomer comprising two or three epoxygroups, at least one hydroxylated epoxy monomer comprising at leastthree epoxy groups and one to three hydroxyl groups, at least one UVabsorber comprising a hydroxyphenyl benzotriazole or hydroxyphenyltriazine, and at least one epoxy ring-opening catalyst, and curing theresulting coating with heat. The coating exhibits an adhesion of atleast 96% to said optical substrate upon at least 40 hours of exposureto full spectrum sunlight when tested according to ISTM 02-010. In someembodiments, the optical substrate comprises a thermoset material orhard coated polycarbonate lens.

Other objects, features and advantages will become apparent from thefollowing detailed description. It should be understood, however, thatthe detailed description and the examples, while indicating specificembodiments, are given by way of illustration only. Additionally, it iscontemplated that changes and modifications will become apparent tothose skilled in the art from this detailed description.

DETAILED DESCRIPTION

Various features and advantageous details are explained more fully withreference to the non-limiting embodiments that are detailed in thefollowing description. It should be understood, however, that thedetailed description and the specific examples, while indicatingembodiments, are given by way of illustration only, and not by way oflimitation. Various substitutions, modifications, additions, and/orrearrangements will be apparent to those of ordinary skill in the artfrom this disclosure.

The heat-curable coating compositions disclosed herein employ thecombination of at least one epoxy monomer, at least one hydroxylatedepoxy monomer, at least one uv absorber, and at least one ring-openingcatalyst to prepare a coating that provides durable adhesion, low haze,and strong abrasion resistance following prolonged exposure to sunlight.Moreover, the compositions disclosed herein are compatible with theabsorbing dyes and additives used for many applications, includingblue-cut technology.

Heat-Curable Coating Composition

The epoxy monomers disclosed herein are cyclic ethers and are preferablyepoxides (oxiranes). As used herein, the term “epoxide” represents asubclass of epoxy compounds containing a saturated three-membered cyclicether. The epoxy groups of the epoxy monomer are preferably chosen fromglycidyl groups and cycloaliphatic epoxy groups, more preferably fromalkyl glycidyl ether groups and cycloaliphatic epoxy groups.

In the present disclosure, the term “alkyl” means a linear or branched,saturated or unsaturated monovalent hydrocarbon-based radical,preferably containing from 1 to 25 carbon atoms. The term alkyl includesacyclic groups preferably containing from 1 to 8 carbon atoms, morepreferably from 1 to 6 carbon atoms, such as methyl, ethyl, n-propyl,isopropyl, butyl and n-hexyl groups, and the cycloaliphatic andcycloalkyl groups preferably containing from 3 to 7 carbon atoms, thecycloalkylmethyl groups preferably containing from 4 to 8 carbon atoms.

The term “cycloaliphatic” denotes a saturated or unsaturated butnon-aromatic carbocyclic radical comprising one or several optionallyfused rings, which may optionally be substituted with one or more of thegroups cited above for the aryl group. The term “cycloaliphatic” alsoincludes “heterocycloaliphatic” groups, i.e. non-aromatic monocyclic orpolycyclic rings in which one or more carbon atoms of the ring(s) havebeen replaced with a heteroatom such as nitrogen, oxygen, phosphorus orsulfur. The cycloaliphatic group is preferably a cycloalkyl group.

The term “cycloalkyl” also includes “heterocycloalkyl” groups, i.e.non-aromatic monocyclic or polycyclic rings in which one or more carbonatoms of the ring(s) have been replaced with a heteroatom such asnitrogen, oxygen, phosphorus or sulfur. The heterocycloalkyl grouppreferably comprises 1 to 4 endocyclic heteroatoms. The heterocycloalkylgroups may be structures containing one or more nonaromatic rings.

The term “aryl” denotes an aromatic carbocyclic radical comprising onlyone ring (for example a phenyl group) or several, optionally fused,rings (for example naphthyl or terphenyl groups), which may optionallybe substituted with one or more groups such as, without limitation,alkyl (for example methyl), hydroxyalkyl, aminoalkyl, hydroxyl, thiol,amino, halo (fluoro, bromo, iodo or chloro), nitro, alkylthio, alkoxy(for example methoxy), aryloxy, monoalkylamino, dialkylamino, acyl,carboxyl, alkoxycarbonyl, aryloxycarbonyl, hydroxysulfonyl,alkoxysulfonyl, aryloxysulfonyl, alkylsulfonyl, alkylsulfinyl, cyano,trifluoromethyl, tetrazolyl, carbamoyl, alkylcarbamoyl ordialkylcarbamoyl groups. Alternatively, two adjacent positions of thearomatic ring may be substituted with a methylenedioxy or ethylenedioxygroup. The term “aryl” also includes “heteroaryl” groups, i.e. aromaticrings in which one or more carbon atoms of the aromatic ring(s) havebeen replaced with a heteroatom such as nitrogen, oxygen, phosphorus orsulfur.

The epoxy monomer may have two or three epoxy groups per molecule, anddoes not include any hydrolyzable functional groups directly linked to asilicon atom. In the present disclosure, Si—O—Si groups are consideredas not being hydrolyzable groups. In some embodiments, the epoxy monomerdoes not comprise any silicon atoms.

Examples of hydrolyzable functional groups include but are not limitedto alkoxy groups —O—R¹, wherein R¹ prefereably represents a linear orbranched alkyl or alkoxyalkyl group, preferably a C₁-C₄ alkyl group,acyloxy groups —O—C(O)R², wherein R² preferably represents an alkylgroup, preferably a C₁-C₆ alkyl group, and more preferably a methyl orethyl group, halogen groups such as Cl and Br, amino groups optionallysubstituted with one or two functional groups such as an alkyl or silanegroup, for example, the NHSiMe₃ group, alkylenoxy groups such as theisopropenoxy group, and the hydroxyl group —OH.

In some embodiments, the epoxy monomer does not contain reactivefunctional groups, other than the epoxy groups, such as hydroxyl groups,that are capable of reacting with other polymerizable functional groupspresent in the composition and that would be linked to the polymermatrix of the coating.

In some embodiments, the epoxy monomer is a diglycidyl ether,triglycidyl ether, or a cycloaliphatic epoxy. Glycidyl ethers aresynthetic compounds characterized by the following group in which R₁denotes a monovalent group:

The preferred cycloaliphatic epoxy groups are shown hereunder, in whichthe hydrogen atoms in the structures may be substituted by one or moresubstituents such as those cited above as substituents for an arylgroup:

In some embodiments, the epoxy monomer comprises a 3,4-epoxycyclohexylalkyl group, such as a 3,4-epoxycyclohexyl methyl and a3,4-epoxycyclohexyl ethyl group.

Examples of epoxy monomers include but are not limited totrimethylolethane triglycidyl ether (Erisys® GE-31 from CVC ThermosetSpecialties), trimethylolmethane triglycidyl ether, trimethylolpropanetriglycidyl ether (Erisys® GE-30 from CVC Thermoset Specialties),triphenylolmethane triglycidyl ether, trisphenol triglycidyl ether,tetraphenylol ethane triglycidyl ether, p-aminophenol triglycidyl ether,1,2,6-hexanetriol triglycidyl ether, glycerol triglycidyl ether,diglycerol triglycidyl ether, glycerol ethoxylate triglycidyl ether,castor oil triglycidyl ether, propoxylated glycerine triglycidyl ether,ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether,neopentyl glycol diglycidyl ether, cyclohexanedimethanol diglycidylether, dipropylene glycol diglycidyl ether, polypropylene glycoldiglycidyl ether, dibromoneopentyl glycol diglycidyl ether, hydrogenatedbisphenol A diglycidyl ether (Epalloy 5000 from CVC ThermosetSpecialties), 3′,4′-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (Uvacure® 1500 from Allnex, Cyracure™ UVR-6110 and UVR™ 6105from Dow Chemical Company), bis(3,4-epoxycyclohexylmethyl) adipate(Cyracure™ UVR-6128 from Dow Chemical Company), limonene diepoxide(6-methyl-3-(2-methyloxiran-2-yl)-7-oxabicyclo[4.1.0]heptane, Celloxide®3000 from Daicel Chemical Industries Ltd.),1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]tetramethyldisiloxane (SIB1092.0from Gelest), bisphenol A diglycidyl ether (Epon™ Resin 828 fromHexion), hexahydrophthalic anhydride diglycidyl ester (CY 184 fromCiba), and derivatives thereof, and mixtures thereof.

The at least one hydroxylated epoxy monomer may be a cyclic ether and ispreferably an epoxide (oxirane). The epoxy groups of the hydroxylatedepoxy monomer are preferably chosen from glycidyl groups, morepreferably from alkyl glycidyl ether groups. As used herein, the term“hydroxylated” denotes the presence of one or more hydroxyl groups. Theterm “hydroxyl” denotes an —OH functional group.

In some embodiments, the at least one hydroxylated epoxy monomer has atleast three epoxy groups and one to three hydroxyl groups per molecule.In some aspects, the hydroxylated epoxy monomer does not includehydrolyzable groups directly linked to a silicon atom. In someembodiments, the hydroxylated epoxy monomer does not comprise anysilicon atoms.

Examples of hydrolyzable functional groups include but are not limitedto alkoxy groups —O—R¹, wherein R¹ prefereably represents a linear orbranched alkyl or alkoxyalkyl group, preferably a C₁-C₄ alkyl group,acyloxy groups —O—C(O)R², wherein R² preferably represents an alkylgroup, preferably a C₁-C₆ alkyl group, and more preferably a methyl orethyl group, halogen groups such as Cl and Br, amino groups optionallysubstituted with one or two functional groups such as an alkyl or silanegroup, for example the NHSiMe₃ group, alkylenoxy groups such as theisopropenoxy group, and the hydroxyl group —OH.

Examples of hydroxylated epoxy monomers include but are not limited toglycerol diglycidyl ether, diglycerol tetraglycidyl ether, tetraphenylolethane triglycidyl ether, sorbitol polyglycidyl ether (Erisys GE-60 fromCVC Thermoset Specialties), and derivatives thereof, and mixturesthereof. In some aspects, the at least one hydroxylated epoxy monomer ispreferably the sorbitol polyglycidyl ether Erisys GE-60.

In one embodiment, the heat-curable coating composition comprises 5-30%by weight of hydroxylated epoxy monomers b) according to the invention,as compared to the total weight of the composition. In anotherembodiment, the heat-curable coating composition comprises 10-25% byweight of hydroxylated epoxy monomers b) according to the invention, ascompared to the total weight of the composition.

In one embodiment, the heat-curable coating composition comprises 20-40%by weight of epoxy monomers a) comprising two or three epoxy groups,wherein the epoxy monomer does not include hydrolyzable groups directlylinked to a silicon atom, as compared to the total weight of thecomposition.

In some embodiments, the heat-curable composition comprises at least onedye preferably in an amount ranging from 0.01 to 5% of the weight of thecomposition. In some aspects, the absorbing dye at least partiallyinhibits the transmission of light in at least one selected wavelengthrange between 380 and 1400 nm.

In some aspects, the UV absorber comprises a hydroxyphenyl benzotriazoleor hydroxyphenyl triazine. The UV spectrum has a plurality of bands,including UVA, UVB and UVC bands. Amongst those UV bands reaching theearth surface, UVA band—ranging from 315 nm to 380 nm, and UVBband—ranging from 280 nm to 315 nm—are particularly harmful to theretina. UV absorbers are frequently incorporated in optical articles inorder to reduce or prevent UV light from reaching the retina (inparticular in ophthalmic lens materials), but also to protect thesubstrate material itself, thus preventing it from weathering andbecoming brittle and/or yellow.

The UV absorber preferably has the ability to at least partially blocklight having a wavelength ranging from 10 to 450 nm. The UV absorberpreferably has the ability to at least partially block light having awavelength shorter than 400 nm, preferably UV wavelengths below 385 or390 nm, but also has an absorption spectrum extending to the visibleblue light range (400-500 nm).

In addition to UV absorbing functionality, the UV absorber enhances theadhesion of the resulting dry coating composition to an opticalsubstrate. While the UV absorber may provide some adhesion improvementswhen combined with an epoxy monomer, such as trimethylolethanetriglycidyl ether (Erisys GE-31), the inclusion of the UV absorber withboth an epoxy monomer and a hydroxylated epoxy monomer in the coatingcomposition provides significant improvements in adhesion.

The UV absorbers capable of enhancing adhesion belong to thehydroxyphenyl benzotriazole or hydroxyphenyl triazine families. Examplesof preferable hydroxyphenyl benzotriazole UV absorbers include but arenot limited to the family of 2-(2-hydroxyphenyl)-benzotriazoles, such as2-(2-hydroxy-3-t-butyl-5-methylphenyl) chlorobenzotriazole,2-(2′-hydroxy-5′-t-octylphenyl) benzotriazole,2-(3′-methallyl-2′-hydroxy-5′-methyl phenyl) benzotriazole or otherallyl hydroxymethylphenyl benzotriazoles,2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole (Seesorb 701),2-(3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole, and the2-hydroxy-5-acryloxyphenyl-2H-benzotriazoles disclosed in U.S. Pat. No.4,528,311. Examples of preferable hydroxyphenyl triazine UV absorbersinclude but are not limited to Tinuvin® 477 and Tinuvin® 479.

Examples of preferable commercially available UV absorbers include butare not limited to the Tinuvin® and Chimassorb® compounds from BASF,Seesorb 701 and 703 from Shipro Kasei Kaisha, UV-400 from Hunan ChemicalBV, Chiguard® 1063 and Chiguard® 54005 from Chitec Technology Co., Ltd,and Viosorb 550 from Kyodo Chemicals. More specifically, Tinuvin® 477and 479, both hydroxyphenyl triazines, are preferable UV absorbers.

Suitable UV absorbers may be commercially available as a blend of UVabsorbers and hindered-amine light stabilizers (HALS), such as Tinuvin®5151.

Absorbing, or transmittance-attenuating, dyes provide localized regionsof reduced light transmission across specific wavelength regions, i.e.,localized transmittance minima. By incorporating dyes that reduce lighttransmittance across specific regions, non-reduced wavelength regionsappear as regions with relatively higher transmittance, i.e., localizedtransmittance maxima. The inclusion of specific dyes into a lensenhances color contrast by tuning local minima and maxima to achieve thedesired transmission spectrum.

Absorbing dyes can be selected to reduce transmittance across a desiredwavelength range. Dye concentration can be selected to adjust the degreeof reduction in transmittance. The total number of dyes can be adjustedto customize the transmission spectrum. By combining multiple dyes,various transmittance profiles can be tailored for specificapplications. The phrases “transmittance-reducing”,“transmittance-attenuating”, “color absorbing”, or “light absorbing” areused interchangably herein.

The amount and/or identity of an absorbing dye may be selected tobalance the color of light passing through optical articles. The amountand/or identity of an absorbing dye may be selected to impart a color ortint to an optical article. The absorbing dye may be selected from azodyes, polymethyne dyes, arylmethyne dyes, polyene dyes, anthracinedionedyes, pyrazolone dyes, anthraquinone dyes, isoindolinone dyes,auinophtalone dyes, naphthalenediamine dyes, and carbonyl dyes. Specificexamples of such dyes include but are not limited to ABS420, D&C Violet,Savinyl Blue RS, Perox Blue, Solvent Red 135, and Solvaperm Red RR.

In some embodiments, the epoxy ring-opening catalyst facilitates thepolycondensation and/or cross-linking reactions for the epoxy compoundsof the composition. Preferred catalysts are capable of curing the epoxycomposition at temperatures low enough (preferably ≤110° C., morepreferably ≤100° C.) to not damage the underlying substrate and/or causeadverse affects to other coatings or coating components.

In order to obtain storage-stable heat curable compositions, preferredcatalysts do not catalyze the epoxy ring-opening at room temperature.This feature prevents premature polymerization or formation ofpre-polymers in the coating compositions during storage or while inproduction, thereby extending the pot-life and shelf-life. In thisregard, the catalyst is preferably a blocked catalyst or a latentcatalyst (such as a buffered acid catalyst). Blocked catalysts do notreact until reaching their respective de-blocking temperatures. Thepreferred catalysts are inactive at ambient temperature (20° C.) andactivated to catalyze epoxy ring-opening only upon heating, generally to70° C. to 80° C. or more.

Exemplary blocked or latent catalysts are based ontrifluoromethanesulfonic acid (triflic acid), dinonylnaphthalenesulfonic acid, dinonylnaphthalene disulfonic acid (DNNDSA), and ammoniumantimony hexafluoride (a Lewis acid), metal salt of triflic acid (aLewis acid, buffered to reduce its reactivity at ambient temperature).Both triflic acid and metal salts of triflic acid are preferredcatalysts. Other useful catalysts include carboxylic acid anhydridessuch as hexahydrophthalic anhydride, methylhexahydrophthalic anhydride,or Lewis acid catalysts including BF₃ and BCl₃ amine complexes.

In some embodiments, the epoxy ring-opening catalyst is chosen fromaluminum chelates, aluminum acrylates and aluminum alcoholates. Thecomposition preferably does not contain other epoxy ring-openingcatalysts such as acid catalysts or ammonium salts of metal anions whenaluminum catalysts are employed. Preferred aluminum acrylates andaluminum alcoholates are of the general formulaeAl(OC(O)R)_(n)(OR′)_(3-n) and Al(OSiR″3)_(n)(OR')_(3-n), wherein R andR′ are linear or branched chain alkyl groups containing from 1 to 10carbon atoms, R″ is a linear or branched chain, alkyl group containingfrom 1 to 10 carbon atoms, a phenyl moiety, an acrylate moiety offormula OC(O)R, wherein R is as defined just hereabove, and n is aninteger from 1 to 3. Preferably, R′ is an isopropyl or ethyl group, Rand R″ are methyl groups.

The epoxy ring-opening catalyst may be used in an amount ranging from0.1-5% by weight based on the weight of the composition, preferably from0.2 to 3.5% by weight, more preferably from 0.5 to 3% by weight.

In some embodiments, the heat-curable composition further comprises atleast one epoxysilane or hydrolyzate thereof having at least onehydrolyzable group directly linked to the silicon atom and at least oneepoxy group. The epoxysilane preferably has from 2 to 6, more preferably2 or 3 hydrolyzable functional groups directly linked to the siliconatom that lead to an OH group upon hydrolysis. Examples of hydrolyzablefunctional groups include but are not limited to alkoxy groups —O—R¹,wherein R¹ prefereably represents a linear or branched alkyl oralkoxyalkyl group, preferably a C₁-C₄ alkyl group, acyloxy groups—O—C(O)R², wherein R² preferably represents an alkyl group, preferably aC₁-C₆ alkyl group, and more preferably a methyl or ethyl group, halogengroups such as Cl and Br, amino groups optionally substituted with oneor two functional groups such as an alkyl or silane group, for example,the NHSiMe₃ group, alkylenoxy groups such as the isopropenoxy group, andthe hydroxyl group —OH.

Preferred epoxysilanes are epoxyalkoxysilanes, and more preferred arethose having one epoxy group and three alkoxy groups. The epoxy groupsof the epoxysilane are preferably chosen from glycidyl groups andcycloaliphatic epoxy groups, more preferably from alkyl glycidyl ethergroups and cycloaliphatic epoxy groups.

Examples of such epoxysilanes include X-glycidoxypropyl triethoxysilane,λ-glycidoxypropyl trimethoxysilane (GLYMO), 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyl methyldiethoxysilane,2-(3,4-epoxycyclohexyl) ethyltriethoxysilane. Among those silanes,γ-glycidoxypropyltrimethoxysilane (GLYMO) is preferred.

In some embodiments, the epoxysilane is hydrolyzed before being mixedwith the other components of the composition. The hydrolysis may beperformed as known in the art, by using acidic catalysts (e.g.,hydrochloric acid or acetic acid), in the presence of water.

In some embodiments, the epoxysilane is used in an amount of less than30% by weight relative to the total weight of the composition,preferably less than 20% by weight. This amount can be less than 10% orless than 5% by weight and even 0%. Even though the epoxysilane isgenerally hydrolyzed prior to mixing with other components of thecomposition, the amount of epoxysilane will be conventionally defined asthe weight of the initial precursor before its hydrolysis.

The heat-curable composition may also comprise several additives, suchas surfactants, free radical scavengers, and antioxidants.

Methods of Preparing Optical Articles

A substrate should be understood to mean an uncoated substrate andgenerally has two main faces. The substrate may in particular be anoptically transparent material having the shape of an optical article,for example an ophthalmic lens destined to be mounted in glasses. Inthis context, the term “substrate” is understood to mean the baseconstituent material of the optical lens and more particularly of theophthalmic lens. This material acts as support for a stack of one ormore functional coatings or layers.

The substrate of the optical article, coated on at least one main facewith a coating, may be a mineral or an organic glass, for instance anorganic glass made from a thermoplastic or thermosetting plastic,generally chosen from transparent materials of ophthalmic grade used inthe ophthalmic industry.

To be mentioned as especially preferred classes of substrate materialsare polycarbonates, polyamides, polyimides, polysulfones, copolymers ofpolyethylene therephthalate and polycarbonate, polyolefins such aspolynorbornenes, resins resulting from polymerization or(co)polymerization of alkylene glycol bis allyl carbonates such aspolymers and copolymers of diethylene glycol bis(allylcarbonate)(marketed, for instance, under the trade name CR-39® by the PPGIndustries company), polycarbonates such as those derived from bisphenolA, (meth)acrylic or thio(meth)acrylic polymers and copolymers such aspolymethyl methacrylate (PMMA), urethane and thiourethane polymers andcopolymers, epoxy polymers and copolymers, episulfide polymers andcopolymers.

Prior to depositing coatings, the surface of the substrate is usuallysubmitted to a physical or chemical surface activating and cleaningtreatment, so as to improve the adhesion of the layer to be deposited,such as disclosed in WO 2013/013929.

In some aspects, the epoxy coating is deposited on the optical substrateof the optical article and is preferably in direct contact with saidsubstrate. The deposition is carried out using methods known in the art,preferably by spin-coating, spray-coating, 3D printing, roll-to-rollcoating, or inkjet printing the heat-curable composition.

Curing the heat-curable composition can be performed in one or twosteps, including a first pre-curing step to a temperature of at least60° C., preferably at least 70° C., more preferably at least 75° C.,typically from 75° C. to 100° C. or from 80° C. to 100° C., for at least5 minutes, generally from 10 to 25 or 30 minutes, typically 15 minutes,so as to form a tack-free coating, and a second step of heating theoptical article coated with the tack-free coating to a temperaturehigher than or equal to the temperature of the pre-curing step,preferably at least 90° C. or 95° C., more preferably at least 98° C. or100° C., typically from 100° C. to 140° C., preferably from 100° C. to115° C., for 1 to 3 hours, generally at least two hours, preferably for2.5 to 3.5 hours, typically 3 hours, so as to obtain a completely curedinsoluble coating. Alternative coating curing process is a first curingstep to a temperature of 100° C., preferably at least 110° C., morepreferably at least 125° C., for at least 30 minutes, generally 60minutes, and a second step to a temperature lower than the first step,preferably 100° C. or less, preferably at 80° C. for 30 minutes,generally 60 minutes. The process leads to transparent clear coatingswith low haze.

The thickness of the cured coating may be adapted to the specificapplication required and generally ranges from 0.5 to 50 μm, preferablyfrom 1 to 20 μm, more preferably from 2 to 10 μm.

Optical Article

Any embodiment of any of the disclosed compositions and/or methods canconsist of or consist essentially of—rather thancomprise/include/contain/have—any of the described elements and/orfeatures and/or steps. Thus, in any of the claims, the term “consistingof” or “consisting essentially of” can be substituted for any of theopen-ended linking verbs recited above, in order to change the scope ofa given claim from what it would otherwise be using the open-endedlinking verb.

The optical article is preferably a transparent optical article, inparticular an optical lens or lens blank, more preferably an ophthalmiclens or lens blank. The term “ophthalmic lens” is used to mean a lensadapted to a spectacle frame to protect the eye and/or correct thesight. Said lens can be chosen from afocal, unifocal, bifocal, trifocaland progressive lenses. Although ophthalmic optics is a preferred field,it will be understood that the embodiments disclosed herein can beapplied to optical elements of other types where filtering specifiedwavelengths may be beneficial, such as, for example, lenses for opticalinstruments, safety goggles, filters particularly for photography,astronomy or the automobile industry, optical sighting lenses, ocularvisors, optics of lighting systems, screens, glazings, etc.

If the optical article is an optical lens, it may be coated on its frontmain surface, rear main side, or both sides with a coating or coatingsas disclosed herein. As used herein, the rear face of the substrate isintended to mean the face which, when using the article, is the nearestfrom the wearer's eye. It is generally a concave face. On the contrary,the front face of the substrate is the face which, when using thearticle, is the most distant from the wearer's eye. It is generally aconvex face. The optical article can also be a plano article, that is,an optical article that does not provide visual correction.

As used herein, a coating that is “on” a substrate/coating or which hasbeen deposited “onto” a substrate/coating is defined as a coating that(i) is positioned above the substrate/coating, (ii) is not necessarilyin contact with the substrate/coating, that is to say one or moreintermediate coating(s) may be interleaved between the substrate/coatingand the relevant coating (however, it does preferably contact saidsubstrate/coating), and (iii) does not necessarily completely cover thesubstrate/coating. When a first coating is said to be located under asecond coating, it should be understood that the second coating is moredistant from the substrate than the first coating.

The term “substantially” and its variations are defined as being largelybut not necessarily wholly what is specified as understood by one ofordinary skill in the art, and in one non-limiting embodimentsubstantially refers to ranges within 10%, within 5%, within 1%, orwithin 0.5%.

“Derivative,” in relation to a parent compound, refers to a chemicallymodified parent compound or an analogue thereof, wherein at least onesubstituent is not present in the parent compound or an analoguethereof. One such non-limiting example is a parent compound which hasbeen covalently modified. Typical modifications are amides,carbohydrates, alkyl groups, acyl groups, esters, pegylations and thelike.

The term “about” or “approximately” or “substantially unchanged” aredefined as being close to as understood by one of ordinary skill in theart, and in one non-limiting embodiment the terms are defined to bewithin 10%, preferably within 5%, more preferably within 1%, and mostpreferably within 0.5%.

The use of the word “a” or “an” when used in conjunction with the term“comprising” in the claims and/or the specification may mean “one,” butit is also consistent with the meaning of “one or more,” “at least one,”and “one or more than one.”

As used in this specification and claim(s), the words “comprising” (andany form of comprising, such as “comprise” and “comprises”), “having”(and any form of having, such as “have” and “has”), “including” (and anyform of including, such as “includes” and “include”) or “containing”(and any form of containing, such as “contains” and “contain”) areinclusive or open-ended and do not exclude additional, unrecitedelements or method steps.

The compositions and methods for their use can “comprise,” “consistessentially of,” or “consist of” any of the ingredients or stepsdisclosed throughout the specification.

EXAMPLES Preparation of Wet Coating Compositions C1-C4

Four preliminary epoxy solutions were prepared by mixing3′,4′-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate (epoxymonomer 1, Uvacure® 1500), trimethylol ethane triglycidyl ether (epoxymonomer 2, Erisys GE-31), sorbitol polyglycidyl ether (hydroxylatedepoxy monomer, Erisys GE-60), and a solvent comprising propylene glycolmethyl ether as the major isomer (Dowanol PM) in one container andallowed to stir for 30 minutes. C1, prepared without a hydroxylatedepoxy monomer, was the reference coating.

The preliminary epoxy solutions were then combined with an antimonyhexafluoride based catalyst for thermal initiated cationicpolymerization (CXC-1612), propylene carbonate, methanol, aluminumacetylacetonate (Al(AcAc)₃, epoxy ring-opening catalyst), and afluoroaliphatic polymeric ester surfactant in dipropylene glycol(Fluorad FC-4434, surfactant), and mixed for 30 minutes.

In another container, (3-glycidyloxypropyl)trimethoxysilane (GLYMO,epoxysilane monomer) was mixed with 0.1 N HCl for at least one hour thenadded to the four combined solutions prepared above and mixed for 30minutes. The percentages of each component in the wet coatingcomposition of examples C1-C4 are shown in Table 1.

TABLE 1 Wet Coating Compositions for Examples C1-C4 (hydroxylated epoxymonomer, no UV absorber) Wet Coating Compositions Component C1 C2 C3 C4Epoxy monomer 1 (Uvacure ® 1500) 26.39 25.98 25.12 21.99 Epoxy monomer 2(Erisys GE-31) 9.90 9.75 9.42 8.25 Hydroxylated epoxy monomer 0.00 1.554.81 16.69 (Erisys GE-60) Epoxy ring-opening catalyst 1.48 1.46 1.411.24 (Al(AcAc)₃) Surfactant (Fluorad FC-4434) 0.20 0.20 0.19 0.17Solvent (Dowanol PM) 50.18 49.40 47.77 41.80 Methanol 5.84 5.75 5.564.87 Epoxysilane monomer (GLYMO) 4.89 4.81 4.66 4.07 0.1N HCl 1.12 1.101.06 0.92

Different finished single vision (FSV) lenses (CR-39, Trivex, PDQ PC, orMR7) and semi-finished (SF) lenses (MR8 or 1.74) were first cleaned withsoap and water and dried. Next, the convex side of each lens was coronatreated for 15-30 seconds. Finally, the lenses were cleaned withdeionized water and dried. Each lens was spin coated with the abovecoating composition solutions (C1, C2, C3, and C4) at fixed speeds (400rpm/8 s and 800 rpm/10 s). The lenses were then pre-cured at 80° C. for15 minutes and further cured at 100° C. for 3 hours. The thicknesses ofthe resulting dry coatings on the lenses were between 4 and 7 μm.

Evaluation of C1-C4 Dry Coating Performance

A dry adhesion test, referred to as a crosshatch tape peel adhesiontest, was performed on coated articles in accordance with the ISTM02-010 standard. The test is performed on coated articles by cutting agrid of 25×1 mm squares using a tool that has six (6) parallel razorblades 1 mm apart. The grid is cut into the coating at least 5 to 10 mmfrom the edge of the lens. Then, a piece of 3M SCOTCH 600 tape that hasnot been exposed to air is removed from the roll and applied uniformlyto the grid using a plastic spatula with approximately 15 to 20 mm oftape off of the edge of the lens. The tape is quickly removed from thelens with a sharp, rapid continuous movement. This is repeated 5 timeson the same grid.

The adhesion performance of the coating is scored on a scale from 0 to5. An adhesion score of 0 refers to no coating loss. Adhesion is scoredas follows:

TABLE 2 Adhesion Test Scoring Adhesion Squares Area % Left Score RemovedIntact 0  0 100 1 <1  96-100 2 1 to 4 84-96 3 >4 to 9  64-84 4 >9 to 1636-64 5 >16  <36

Simulated Ageing

After the coatings are evaluated by a dry adhesion test, each examplelens is subjected to the Q-sun test to simulate the effects of sunlightexposure upon the coated optical article. The Q-sun test consists ofplacing the coated optical articles in a Q-sun® Xe-3 xenon chamber,which reproduces full spectrum sunlight, at a relative humidity of 20%(±5%) and at a temperature of 23° C. (±5° C.), and exposing their convexside to the light for one cycle or two cycles (40 hours in each cycle).If the lens is rated as 0 or 1 in the dry adhesion test, it is furthertested in the Q-sun test for one or two cycles; if it is rated as 2 orabove in the dry adhesion test or the first cycle of 40 hours, there isno following adhesion test (n/a).

The adhesion scores of each example coating (C1-C4) on each substrate,before and after 40 or 80 hours of Q-sun exposure, are shown in Table 3.The dry coatings of comparative examples C1-C4 show that increasingamounts of hydroxylated epoxy monomer (GE-60) provide improved initialadhesion on high-index substrates before and after Q-sun exposure. TheC4 coatings (having relatively higher hydroxylated epoxy monomercontent) exhibited maximum adhesion scores on MR7 and MR8 substrates. Asthe amount of hydroxylated epoxy monomer in the coatings increased, theadhesion properties of the coating on high-index substrates improved.The C4 coatings, however, failed on the 1.74 substrates after 40 hoursof Q-sun exposure. In these substrates, increased amounts ofhydroxylated epoxy monomer may have decreased dye solubility and/orincreased photo-degradation of the dye.

TABLE 3 Adhesion Test Results After Q-Sun Exposure for Examples C1-C4Q-sun (hours) of Dry Coatings on different lens substrates Wet CoatingCompositions C1 C2 C3 C4 Lens 0 40 80 0 40 80 0 40 80 0 40 80 substrateTrivex 0 0 0 0 0 0 0 0 0 0 0 0 PDQ PC 0 0 0 0 0 0 0 0 0 0 0 0 MR7 0 5n/a 0 3 n/a 0 1 5 0 0 0 MR8 5 n/a n/a 4 n/a n/a 1 5 n/a 0 0 0 1.74 n/an/a n/a n/a n/a n/a n/a n/a n/a 0 4 n/aComparative Examples with UV Absorbers

Comparative coating composition solutions (C5-C11) were prepared usingthe same procedure as C1 above except that each solution included a UVabsorber selected from the group consisting of: Tinuvin® CarboProtect(TCP), Tinuvin® 477 (T477), Tinuvin® 479 (T479), and Tinuvin® 1130(T1130). The compositions of comparative examples C9, C10, and C11contain approximately twice as much of its respective UV absorber asexamples C5, C7, and C8. The percentages of each component in the wetcoating composition of examples C5-C11 are shown in Table 3.

TABLE 4 Wet Coating Compositions for Examples C5-C11 (UV absorber, nohydroxylated epoxy monomer) Wet Coating Compositions C5 C6 C7 C8 C9 C10C11 Component (% by weight) Epoxy monomer 1 26.22 26.22 26.22 26.2226.06 26.06 26.06 (Uvacure ® 1500) Epoxy monomer 2 9.84 9.84 9.84 9.849.78 9.78 9.78 (Erisys GE-31) Epoxy ring-opening 1.47 1.47 1.47 1.471.46 1.46 1.46 catalyst (Al(AcAc)3) Surfactant 0.20 0.20 0.20 0.20 0.200.20 0.20 (Fluorad FC-4434) Epoxysilane monomer 4.86 4.86 4.86 4.86 4.834.83 4.83 (GLYMO) Solvent 49.87 49.87 49.87 49.87 49.56 49.56 49.56(Dowanol PM) Methanol 5.80 5.80 5.80 5.80 5.77 5.77 5.77 0.1N HCl 1.111.11 1.11 1.11 1.11 1.11 1.11 UV Absorber TCP 0.62 0 0 0 1.25 0 0 T477 00.62 0 0 0 0 0 T479 0 0 0.62 0 0 1.25 0 T1130 0 0 0 1.25 0 0 1.25

Evaluation of C5-C11 Dry Coating Performance

Each of the above coating compositions (C5-C11) were spin-coated on aMR7 lens substrate and cured according to the same procedure as exampleC1 above. The adhesion scores of each example coating (C5-C11) on thehigh-index MR7 substrate, before and/or after 40 or 80 hours of Q-sunexposure, are shown in Table 5. Three of the coatings containing TCP,T477, and T479 (C5, C6, and C7, respectively) exhibited slight adhesionimprovements on the high index substrate (MR7) when compared to thereference example (C1); however, the coating containing T1130 (C8)showed no improvement over the reference example. The UV absorbers, ontheir own, do not induce sufficient adhesion of the coating on a highindex substrate after Q-sun exposure. All of the coatings failed theadhesion test on the MR7 substrate after 0 or 40 hours of Q-sunexposure. Furthermore, doubling the amount of UV absorbers in thecomposition (C9-C11) significantly decreased adhesion of the coatingseven without Q-sun exposure.

TABLE 5 Adhesion Test Results After Q-Sun Exposure for Examples C5-C11Dry Coating C5 C6 C7 C8 Q-sun 0 40 80 0 40 80 0 40 80 0 40 80 (hours)MR7 0 3 n/a 0 4 n/a 0 2 n/a 0 5 n/a lens Dry Coating C9 C10 C11 Q-sun 040 80 0 40 80 0 40 80 (hours) MR7 5 n/a n/a 5 n/a n/a 5 n/a n/a lens

Examples Including Hydroxylated Epoxy Monomers and UV Absorbers (D1-D5)

The following coating composition solutions (D1-D5) were prepared usingthe same procedure as above, but each solution included both ahydroxylated epoxy monomer (GE-60) and a UV absorber (T479 or T1130).The ratios of hydroxylated epoxy monomer to UV absorber was varied forthe different coating composition solutions to obtain optimal coatingadhesion on high-index substrates (MR7, MR8, and 1.74 lenses). Thepercentages of each component in the wet coating composition ofinventive examples D1-D5 are shown in Table 6.

TABLE 6 Wet Coating Compositions for Examples D1-D5 (UV absorber +hydroxylated epoxy monomer) Wet Coating Compositions D1 D2 D3 D4 D5Component (% by weight) Epoxy monomer 1 22.51 21.49 21.37 20.78 21.08(Uvacure 1500) Epoxy monomer 2 8.44 8.06 8.02 7.80 7.91 (Erisys GE-31)Hydroxylated epoxy monomer 13.22 17.1 17 20.47 17.17 (Erisys GE-60)Epoxy ring-opening catalyst 1.26 1.21 1.20 1.17 1.18 (Al(AcAc)3)Surfactant 0.17 0.16 0.16 0.16 0.16 (Fluorad FC-4434) Epoxysilanemonomer 4.17 3.98 3.96 3.85 3.91 (GLYMO) Solvent 42.8 40.86 40.63 39.5140.03 (Dowanol PM) Methanol 4.98 4.75 4.73 4.6 4.66 0.1N HCl 0.95 0.910.91 0.88 0.89 UV Absorber T479 1.49 1.49 2.02 0.79 T1130 3.00

Evaluation of D1-D5 Dry Coating Performance

Coating compositions D1, D2, and D3 were each spin-coated onto sixdifferent optical substrates (CR-39, Trivex, PDQ PC, MR7, MR8, and 1.74lenses), and cured according to the same procedure as example Cl above.Coating compositions D4 and D5 were only coated onto the 1.74 lenses,the highest-index optical substrates, but were otherwise prepared in thesame manner as examples D1-D3.

The adhesion scores for each dry coating example (D1-D3) on each opticalsubstrate, before and after 40 or 80 hours of Q-sun exposure, are shownin Table 7. Each coating example exhibited excellent adhesion on everysubstrate even after 80 hours of Q-sun exposure. The adhesionimprovement for the combination of hydroxylated epoxy monomers and UVabsorbers exceeds any improvement expected based upon the results of thecoatings containing only one of the components.

TABLE 7 Adhesion Test Results After Q-Sun Exposure for Examples D1-D3Dry Coating D1 D2 D3 Q-sun 0 40 80 0 40 80 0 40 80 (hours) CR-39 0 0 0 00 0 0 0 0 Trivex 0 0 0 0 0 0 0 0 0 PDQ PC 0 0 0 0 0 0 0 0 0 MR7 0 0 0 00 0 0 0 0 MR8 0 0 0 0 0 0 0 0 0 1.74 0 0 0 0 0 0 0 0 0

To further examine dry coating examples D1-D3, CR-39 lenses with the drycoatings were subjected to haze and abrasion resistance tests. Theresults of those tests are shown in Table 8. Despite varying the ratioof GE-60 and T479 in D1, D2, and D3, the results of all three examplesindicate low haze and sufficient abrasion resistance.

Haze was measured as disclosed in WO 2012/173596, on a Hazeguard XL 211Plus apparatus from BYK-Gardner in accordance with the standard ASTMD1003-00. As haze is a measurement of the percentage of transmittedlight scattered more than 2.5° from the axis of the incident light, thesmaller the haze value, the lower the degree of cloudiness. Generally,for optical articles described herein, a haze value of less than orequal to 0.3% is acceptable, more preferably of less than or equal to0.2%.

TABLE 8 Haze and Sand Bayer Results for Dry Coating Examples D1-D3 onCR-39 Lenses Dry Coating D1 D2 D3 Haze, % 0.1 0.1 0.1 Abrasion 0.7-0.8~0.7 ~0.6

Specific Application: Blue-Cut Filter Lenses

A coating composition (D6) similar to low haze and abrasion-resistantcoating example D2 was prepared. Coating composition D6 was prepared bymixing three blue cut dyes (ABS420, D&C Violet, and Savinyl Blue RS)with epoxy monomer 1 (Uvacure 1500,3′,4′-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate), andpropylene glycol methyl ether (solvent, Dowanol PM) in one container,and stirring for 30 minutes to create an epoxy solution. Epoxy monomer 2(trimethylol ethane triglycidyl ether, Erisys GE-31), hydroxylated epoxymonomer (sorbitol polyglycidyl ether, Erisys GE-60), epoxy ring-openingcatalyst (aluminum acetylacetonate, Al(AcAc)₃), surfactant (FluoradFC-4434), and additional solvent (methanol) were added to the epoxysolution and stirred for 30 minutes to 1 hour. In a separate container,epoxysilane monomer ((3-glycidyloxypropyl)trimethoxysilane, GLYMO) wasmixed with 0.1 N HCl for at least one hour, added to the previouslymixed epoxy solution, and stirred for 30 additional minutes. Thepercentages of each component in the wet coating composition of exampleD6 is shown in Table 9. The composition of example 16 is similar to thecomposition of example D2.

TABLE 9 Wet Coating Composition for Example D6 D6 Component (% byweight) w/Blue Cut Dyes Epoxy monomer 1 (Uvacure ® 1500) 21.48 Epoxymonomer 2 (Erisys GE-31) 8.05 Hydroxylated epoxy monomer (Erisys GE-60)17.09 UV Absorber (Tinuvin ® 479) 1.49 Blue-cut dye 1 (ABS420) 0.02Color balance 2 (D&C Violet) 0.02 Color balance dye 3 (Savinyl Blue RS)0.01 Epoxy ring-opening catalyst (Al(AcAc)₃) 1.21 Surfactant (FluoradFC-4434) 0.16 Epoxysilane monomer (GLYMO) 3.98 Solvent 1 (Dowanol PM)40.83 Solvent 2 (methanol) 4.75 0.1N HCl 0.91

The convex sidse of three lenses (two CR-39 lenses and one PDQ PC lens)were first corona treated for 15-30 seconds. The lenses were thencleaned with soap and water and dried. Each lens was spin coated withthe above coating composition solution (D6) at fixed speeds (400 rpm/8 sand 800 rpm/10 s). The lenses were then pre-cured at 80° C. for 15minutes and further cured at 100° C. for 3 hours. The thicknesses of theresulting dry coatings on the lenses were between 5.4 and 6.5 μm.

Evaluation of D6 Dry Coating Performance

The coating on all three lenses showed the same adhesive performances asthe coatings on the same lenses in example D2. Additionalcharacteristics such as haze, abrasion resistance, and blue cutperformance (BVC %) for the dry coatings are shown below in Table 10.

The light transmission factor in the visible spectrum Tv was measured intransmission mode (incidence angle:)0° from a wearer's view angle usinga Cary 50 spectrophotometer from Hunter, with the back (concave) side ofthe lens (2 mm thickness at the center) facing the detector and lightincoming on the front side of the lens. Tv was measured under D65illumination conditions (daylight).

Protection from phototoxic blue light by the inventive coating can beevidenced by calculating the mean blue light protection factor BVCbetween 400 nm and 450 nm, weighted by the light hazard function B′(λ),based on the transmission spectrum. Such factor is defined through thefollowing relation and measured at 0° incidence:

${BVC} = {{100\%} - \frac{\overset{450}{\int\limits_{400}}{{{B^{\prime}(\lambda)} \cdot {T(\lambda)} \cdot d}\;\lambda}}{\overset{450}{\int\limits_{400}}{{{B^{\prime}(\lambda)} \cdot d}\;\lambda}}}$

wherein T(λ) represents the lens transmission factor at a givenwavelength, measured at an incident angle between 0 to 17° , preferablyat 0° , and B′(λ) represents the light hazard function shown on FIG. 1of publication WO 2017/077359, in the name of the Applicant (relativespectral function efficiency). Said light hazard function results fromwork between Paris Vision Institute and Essilor International. It can beseen on this figure that blue light is the most dangerous to human eyeat 428-431 nm. A few values of the B′(λ) function between 400 and 450 nmare given hereunder:

Wavelength (nm) Weighting coefficient B′(λ) 400 0.1618 410 03263 4200.8496 430 1.00 440 0.6469 450 0.4237

TABLE 10 Haze, Sand Bayer, and Blue Cut Results for Dry Coating ExampleD6 Coating D6(a) D6(b) D6(c) FSV Plano Lens CR-39 CR-39 PDQ PC Thickness(μm) 5.4 6.5 5.5 Haze (%) 0.1 0.1 0.2 Abrasion 0.7 0.7 0.6 BVC (%) 24 2729

In a separate set of experiments, FSV CR-39 plano lenses were causticcleaned first, then dip coated with wet coating composition D6 at adraining speed of 1.7 mm/s. The resulting leanses exhibited greater than40% blue cut blocking.

In summary, the inclusion of both a hydroxylated epoxy monomer and a UVabsorber in a heat-curable coating composition results in excellentadhesion on high-index optical substrates, before and after prolongedQ-sun exposure. Moreover, this inventive composition allows for theinclusion of blue-cutting, color-balancing, and other dyes to providedurable, transparent, and effective coatings for optical articles, suchas ophthalmic lenses.

The claims are not to be interpreted as including means-plus- orstep-plus-function limitations, unless such a limitation is explicitlyrecited in a given claim using the phrase(s) “means for” or “step for,”respectively.

1.-15. (canceled)
 16. A heat-curable coating composition, comprising: a)at least one epoxy monomer comprising two or three epoxy groups, whereinthe epoxy monomer does not include hydrolyzable groups directly linkedto a silicon atom; b) at least one hydroxylated epoxy monomer comprisingat least three epoxy groups and one to three hydroxyl groups, whereinthe hydroxylated epoxy monomer does not include hydrolyzable groupsdirectly linked to a silicon atom; c) at least one UV absorbercomprising a hydroxyphenyl benzotriazole or hydroxyphenyl triazine; andd) at least one epoxy ring-opening catalyst.
 17. The composition ofclaim 16, wherein the epoxy monomer is a diglycidyl ether, a triglycidylether, or a cycloaliphatic epoxy.
 18. The composition of claim 16,wherein the hydroxylated epoxy monomer is the sorbitol polyglycidylether Erisys GE-60.
 19. The composition of claim 16, wherein the epoxymonomers and hydroxylated epoxy monomers comprise at least 50% by weightof all epoxy-containing compounds present in the composition.
 20. Thecomposition of claim 16, wherein the composition further comprises atleast one epoxysilane comprising at least one hydrolyzable groupdirectly linked to the silicon atom and at least one epoxy group, or ahydrolyzate thereof.
 21. The composition of claim 20, wherein theepoxysilane is (3-glycidyloxypropyl)trimethoxysilane or hydrolyzed(3-glycidyloxypropyl)trimethoxysilane.
 22. The composition of claim 21,wherein a first epoxy monomer is trimethylol ethane triglycidyl ether, asecond epoxy monomer is 3′,4′-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and a hydroxylated epoxy monomer is the sorbitolpolyglycidyl ether Erisys GE-60.
 23. The composition of claim 16,wherein said epoxy ring-opening catalyst is an aluminum chelate,aluminum acrylate, aluminum alcoholate, triflic acid, or metal salt oftriflic acid.
 24. The composition of claim 16, further comprising atleast one absorbing dye.
 25. The composition of claim 24, wherein theabsorbing dye at least partially inhibits the transmission of light inat least one selected wavelength range between 380 and 1400 nm.
 26. Thecomposition of claim 16, further defined as comprising 5-30% by weightof hydroxylated epoxy monomers b), as compared to the total weight ofthe composition.
 27. The composition of claim 16, further defined ascomprising 10-25% by weight of hydroxylated epoxy monomers b), ascompared to the total weight of the composition.
 28. A method ofpreparing an optical article, comprising: a) coating an opticalsubstrate with the heat-curable coating composition of claim 16; and b)curing the resulting coating with heat.
 29. The method of claim 28,wherein coating an optical substrate comprises spin-coating,spray-coating, 3D printing, roll-to-roll coating, or inkjet printing.30. The method of claim 28, wherein the resulting coating is heated to atemperature between 60° C. and 140° C. to form a tack-free or completelycured coating.
 31. An optical article having at least one main surfacecomprising a coating obtained by depositing on an optical substrate andcuring a composition according to the method of claim 28, wherein saidcoating, following at least 40 hours of exposure to full spectrumsunlight, exhibits an adhesion of at least 96% to said optical substratewhen tested according to ISTM 02-010.
 32. The optical article of claim31, wherein the optical substrate comprises a thermoset material or hardcoated polycarbonate lens.